156639881 has 2 divisors, whose sum is σ = 156639882. Its totient is φ = 156639880.

The previous prime is 156639871. The next prime is 156639941. The reversal of 156639881 is 188936651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 116748025 + 39891856 = 10805^2 + 6316^2 .

It is a cyclic number.

It is not a de Polignac number, because 156639881 - 2²² = 152445577 is a prime.

It is a super-2 number, since 2×156639881² = 49072104639388322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_8796557 and since 156639881 and 8796557 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (156639871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78319940 + 78319941.

It is an arithmetic number, because the mean of its divisors is an integer number (78319941).

Almost surely, 2^156639881 is an apocalyptic number.

It is an amenable number.

156639881 is a deficient number, since it is larger than the sum of its proper divisors (1).

156639881 is an equidigital number, since it uses as much as digits as its factorization.

156639881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 47.

The square root of 156639881 is about 12515.5855236581. The cubic root of 156639881 is about 539.0562860940.

The spelling of 156639881 in words is "one hundred fifty-six million, six hundred thirty-nine thousand, eight hundred eighty-one".